Tracking the Intangible: Quantifying Effort in NFL Running Backs

Emily Shteynberg, Luke Snavely, Sheryl Solorzano

July 25, 2025

What Does It Mean To Give 100%?

Background

  • Effort is intangible and subjective

  • Currently no objective measure of effort exists in the NFL

  • Idea: previous research has explored professional soccer players reaching theoretical max acceleration capacity1

  • Goals:

    • Improve estimation of individual acceleration-speed (A-S) profiles using statistical models

    • Assess how frequently players operate near or exceed their limits as a proxy for effort

Data: 2022 NFL Season1

  • Game, play, player data from Weeks 1-9: 136 games

  • Player tracking data: each observation is a frame in 10 fps

  • Pre-processing:

    • Filtered to running plays where a running back (RB) is the ball carrier

    • Trimmed each play to frames between handoff and end of play

    • Derived directional acceleration

Motivation: Estimate Each RB’s Theoretical Max acceleration Frontier (Morin et al., 2021)

  • Effort = % of a player’s points (frames) close to and above the regression line

But This Approach Has Limitations

  • Gives no credit to low speed points

  • Unrealistic theoretical max speeds - not comparable to soccer

  • Penalizes players for being athletic

  • Does not differentiate between acceleration and deceleration

Effort Metric #1: Quadratic Quantile Regression

Effort Metric #2: Quantile Generalized Additive Model

Computing Effort

Average frame-level effort for each player

\[ \Psi_i = \begin{cases} \frac{1}{1+d_i} & a_i\geq 0 \\ \frac{1}{2}\cdot\frac{1}{1+d_i} & a_i<0 \end{cases} \quad \implies \quad \text{Effort} = \frac{\sum_{i=1}^n \Psi}{n} \]

  • Effort Metric #1:
    • Christian McCaffrey: 16.09%
    • Khalil Herbert: 19.84%
  • Effort Metric #2:
    • Christian McCaffrey: 16.52%
    • Khalil Herbert: 18.81%

Back-up RBs consistently lead in both effort metrics

Effort metrics do not show a strong correlation with play outcomes

Discussion

  • A-S-based effort alone does not explain performance

  • Another way to validate effort metrics?

  • Change the definition of effort? Incorporate game context?

Appendix